mysql union

[webnoob]

i have a three table union and i need to make a condition to only do the union on the table when a condition is true. example:

$querysearch = mysql_query("
(SELECT id, 'Content' AS result, ...)

UNION

(SELECT id, 'Files' AS result, ...)

UNION

(SELECT postid, 'Categories' AS result, ...)

");

when $_GET['foo'] is either 'Content', 'Files, or 'Categories' i want just the results for that union, but when no $_GET['foo'] is present do the union on all 3 tables..as shown above. how can i do this?

thanks for any help.

[coopster]

Write it out, just as you stated it.

if (!isset [php.net]($_GET['foo'])) { 
 $querysearch = mysql_query(" 
  (SELECT id, 'Content' AS result, ...) 
  UNION 
  (SELECT id, 'Files' AS result, ...) 
  UNION 
  (SELECT postid, 'Categories' AS result, ...) 
"); 
}